The present invention relates to plant trays and containers with a detachable screen structure for growing and handling air-pruned plants/seedlings/cuttings/plugs for superior plant growth and to increase agricultural and forestry plant production, including both greenhouse crops and field crops. It relates more particularly to a push-pull air-pruning tray and container structure that allows plant/seedling/cutting/plug removal either from the open bottom or open top of the trays and containers.
Greenhouse utilization is increasing worldwide due to an ever increasing demand for improved crop quality, higher yield per unit area of production, reduced growing time, and reduced production costs. It is estimated that farmers as well as other segments of agriculture are faced with the challenge of producing three times as much food by the year 2040. The further challenge is to produce the extra food on no more land than farming uses today and with fewer environmental side effects than farming has today.
An integral part of greenhouse production is the use of trays and containers for growing plugs, seedlings, cuttings and plants. A common problem associated with traditional tray and containerized production is root tangling and root spiraling, commonly referred to as xe2x80x9croot binding.xe2x80x9d Root binding results in various disadvantages, such as deterring root branching and development, slow and nonuniform growth in trays/pots/containers and after plugs/cuttings/seedlings/plants are transplanted, resulting in significant losses in profits for growers and farmers. Some industry people have been trying to resolve these disadvantages in plant growth, but the basic problems caused by the traditional design remain to be resolved.
In plant culturing practices and automation, the innovative plant root-air-pruning technologies invented by Dr. Barney K. Huang have demonstrated many advantages including: elimination of root-binding, promotion of properly oriented root-branching for increased root-mass and vigorous growth, shortened plant culturing periods, increased yields and quality, increased utilization cycles of greenhouse facilities, savings on growing medium, energy and fertilizer, thus decreasing pollution and improving the environment. The air-pruning tray design also utilizes the plant shoot characteristic that allows the foliage to fold together to go through the top opening as the plant is pulled from the bottom or pushed from the top. This plant characteristic lends itself to an easy dislodging of the plant from the open bottom and facilitates the fully automatic transplanting for labor savings. The root-air-pruning concept allows the development of unique tray systems and simple automated/robotic transplanting systems such as those disclosed by Dr. Barney K. Huang in U.S. Pat. Nos. 3,712,252 5,179,800, 5,254,140, 5,298,041 and 5,573,558. Air-pruning tray-cells/pots have open bottoms with detachable screens. The tray-cells/pots are larger at the bottom and smaller at the top to eliminate the inherent disadvantages of conventional tray-cells/pots that have a smaller closed bottom with drain hole(s) and a larger open top that makes the container-wall tapered outward toward the top resulting in improper wall angle to cause root binding, slow and nonuniform growth.
Numerous field tests indicate that air-pruned plants/seedlings/cuttings/plugs are significantly superior in growth performance both in the trays and after they are transplanted, and that effective fully automatic transplanting can be performed with the air-pruned seedlings for various crops. However, computer optimization technique based on the root development data was not incorporated into the air-pruning tray/container design until recently due to difficulties in obtaining such data and due to the need for a push-pull air-pruning tray and container system as disclosed in the present invention. Because of the difficulties in observing and measuring the actual mechanism of underground root development for qualitative and quantitative evaluation, there is very little information available on this subject matter even in the field of crop sciences, horticulture sciences, or in forestry. This is also due to the fact that many growers, farmers, researchers and extension agents often take commercially available conventional trays/pots/containers for granted without thinking how much the properly designed trays/pots/containers would affect their profits or research results. Many growers and farmers currently own transplanting machines and equipment which were designed for conventional trays/flats/pots/containers, yet, they want to use air-pruning trays/flats/pots/containers which provide them with increased plant production, quality and yields. Therefore, there has been and continues to be a need for air-pruning trays/flats/pots/containers that effectuate root air-pruning but will also allow the air-pruned plants/seedlings/cuttings/plugs to be removed from the top of air-pruning trays and containers.
The present invention entails plant growing air-pruning tray and container systems that are designed to improve overall performance and to overcome the disadvantages and shortcomings of the prior art. In particular, the air-pruning tray and container systems of the present invention are provided with tray-cell and container structure that allows plant removal either from the open bottom or open top of the tray/container. Among the various means disclosed is a detachable supporting screen provided with a series of projecting legs and which is press fitted or slide fitted to the tray/container structure to hold the tray above ground for effective root air pruning and to facilitate cycling watering of the tray culturing system. In one embodiment, the plant container consists of more than one piece of side walls which can be put together to form a self-watering plant container while the bottom screen, provided with a series of projecting legs designed to project into a water-holding bottom pan, is detachably secured to the plant container structure itself The air-pruning trays and containers can have a surrounding edge to hold a water level above the tray and container top so that it can also uniformly water the plants from top of the tray cells and containers.
It is therefore an object of the present invention to provide an air-pruning tray/container structure that allows plant removal either from the open bottom of the tray/container or open top of the tray/container.
Another object of the present invention resides in the provision of a plant tray/container structure with easily attachable and detachable supporting bottom screen that effectuates root air-pruning and which also functions to retain and confine the plant growing medium contained within the plant tray/container systems
Another object of the present invention resides in the provision of a plant tray/container structure having a surrounding edge to hold water for self-watering, having a detachable screen, and to meet the requirements of plastic or metal forming processes for quality mass production at low cost.
A further object of the present invention is to provide air-pruning tray/container systems with increased rigidity that are self-supporting, relatively durable and maintenance-free, and made for easy handling and shipping of the air-pruned plants/seedlings/cuttings/plugs in the tray/container systems.
Still a further object of invention is to provide a plant tray/container system with an easily and quickly attachable and detachable bottom tray/container screen so that it can be adaptable to a fully automatic transplanter which requires easy handling of a large number of air-pruned seedlings.
Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings, which are merely illustrative of such an invention.